Field of the Invention
The present invention relates to a discharging circuit and power supply apparatus, and especially relates to a speedy discharging circuit and a power supply apparatus with the speedy discharging circuit.
Description of the Related Art
The power supply is a very common electronic apparatus. The power supply supplies power to the electronic apparatus to drive the electronic apparatus. Therefore, the power supply is very important. Usually, the power supply receives the alternating current power and converts the alternating current power into the output direct current power.
Nowadays, a conventional power supply comprises two different output voltages: the high voltage (for examples, 32 volts, 30 volts or 24 volts etc.) and the low voltage (for examples, 15 volts, 12 volts or 5 volts etc.). The output voltage of the power supply is the high voltage when the power supply works in the normal mode (for example, supplying power to the electronic apparatus). The output voltage of the power supply is changed to be the low voltage for energy saving when the power supply is in the sleeping mode or the standby mode. The switching time of being changed from the high voltage to the low voltage will be prolonged because there is an output side capacitor arranged in the output side of the power supply. This will cause that the time for entering the sleeping mode or the standby mode detected by the system will be prolonged. Therefore, at this time, the output side capacitor of the power supply has to discharge speedily, so that the electric potential of the output side capacitor of the power supply is the low electric potential.
However, the disadvantage of the conventional power supply is that the output side capacitor of the power supply cannot discharge speedily when the output voltage of the power supply is changed from the high voltage to the low voltage.